This document summarizes the construction and working of a semi-continuous centrifuge. It has a perforated basket that rotates horizontally on a shaft. Feed is introduced and centrifugal force separates undersized crystals that remain in the basket from the liquid that passes through. When the cake reaches a certain height, the inlet stops and it is washed before a knife-chute assembly cuts and collects the cake. Semi-continuous centrifuges can separate crystals from liquids faster than batch centrifuges but use more power and risk crystal breakage during discharge.

1. Pharmaceutical
Engineering
Semi-Continuous
Centrifuge
By : Ishika Choudhary
b.Pharma ;3rd semester
Roll no. 51
Enroll no. AJU190857

2. Semi-continuous
centrifuge
• Semi-continuous centrifuge also called as short-
cycle centrifuge.

3. Construction :
• E- shaped basket with perforation (holes) over the surface.
• The basket mounted on horizontal shaft which runs
continuously by motor.
• Feed or suspension is introduced through feed pipe.
• At the top of the centrifuge, a filter medium is attached .
• There is provision of wash pipe which is used to wash the
crystals.
• The thickness of feed depends on the feeler which rides over
the feed.
• The layer of cake is removed by a chute fitted with a knife.
• The knife cuts down the cake within the basket.
• The knife-chute assembly is raised with the help of a hydraulic
apparatus.
• The solid collected through the hopper.

5. Working :
• Load the slurry into the perforated basket through feed.
• Basket starts to rotate horizontally with the help of
shaft.
• Due to the rotation of basket , centrifugal force arises
which helps in separation.
• The slurry passes through the perforated side , thus the
under-sized materials in the form of crystals remains
inside the basket.
• The required filtered crystals(50-70mm) eliminated
from the outlet.
• When height of the cake(over-size material) is about 2-3
inches , the suspension inlet is stopped.
• The cake is washed with water supplied through the
wash pipe.
• The hydraulic apparatus raises the knife-chute
assembly to cut the cake.
• The cake is collected through the chute.
• The separated liquid is collected through the liquid
outlet.

6. Advantages :
• Used to separate crystals from mother-liquor.
• Used to clarify liquids by removing unwanted
solids dirt from oils.
• Solids can recovered at a faster rate from a
dispersion than batch type centrifuge.
• Complicated process.
• Chances of breakage of crystals during discharge.
• High power consumption.
• An efficient variant of perforated basket centrifuge.

7. Thank you